1. Field of the Invention
The present invention relates in general to springs, and more particularly to plate springs used in an exhaust pipe line of an internal combustion engine. More specifically, the present invention is concerned with circular plate springs for use in a so-called flexible pipe unit installed in the exhaust pipe line to absorb or compensate inevitable dimensional change of the pipe line during practical usage of the same.
2. Description of the Prior Art
Various flexible pipe units have been proposed and put into practical use. As is known, the flexible pipe unit is a device installed in an exhaust pipe line for absorbing or compensating an inevitable dimensional change of the pipe line during practical use of the same. For achieving this compensating function, the flexible pipe unit has a spring or springs installed therein. Some of the springs are of a circular plate type. However, due to their inherent construction, some of the springs of this circular plate type have failed to exhibit a satisfied spring function when installed in the flexible pipe unit.